The endoplasmic reticulum (ER) is the site of production of most transmembrane proteins and lipids for cell organelles. The ER captures proteins from the cytosol as they are synthesized, and these proteins are transmembrane proteins or soluble proteins. The soluble proteins are fully translocated across the membrane and released into the ER lumen. In contrast, transmembrane proteins are only partially translocated across the ER membrane. During the course of protein synthesis and processing, the proteins fold to form their tertiary structure.
When cells are exposed to conditions that disrupt protein folding in the ER, the transcription of genes encoding ER proteins may be upregulated. An unfolded protein response (UPR) exists in cells; this response follows detection of unfolded protein in the ER lumen. During the response, a signal is transduced across the ER membrane to activate transcription of selected genes in the nucleus.
Stress and stress responses can have many deleterious effects on an organism. There is a need in the art for additional therapeutic compositions to modulate stress responses.